The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Operation of a read/write head may be governed by a control interface that includes a hard disk controller (HDC), for providing high level read and write commands and for controlling and adjusting positioning of the read/write head, and a read/write channel (RWC), for reading and writing data and passing information to and from the HDC. The HDC is typically aware of a format of media that is read from and/or written to, and the HDC instructs the RWC to perform various operations, including data read, data write, and servo read operations. The HDC typically initiates these operations by asserting gating signals that are received by the RWC.
The HDC and RWC may operate according to clocks having different resolutions. For example, a clock for the HDC may operate at a symbol-level resolution, while a clock for the RWC may operate at a bit-level resolution. Gating signals provided by the HDC to the RWC may therefore fail to achieve bit-level synchronization with the media since they are generated with only symbol-level resolution.
For continuous recording, an absence of bit-level synchronization between gating signals of the HDC and media creates an uncertainty in a sector starting location on the media. This may lead to lower recording densities on the media, in order to assure that sufficient gaps are present between adjacent sectors to prevent write operations from corrupting adjacent sectors on the media.
In continuous recording, locations of bit islands (or domains) on media are determined during the writing process itself. In Bit Pattern Recording (BPR), bit islands are printed (or etched) onto media during manufacturing. Therefore, bit-level synchronization of a write head with media is necessary in BPR. If a clock governing operation of the write head is not synchronized with the printed bits, then information may not be written correctly to the media.
One method to achieve bit-level synchronization between a write head and media is to operate the HDC on a bit-level clock (e.g., synchronized to the RWC clock). However, this increases system complexity as logic related to the HDC will be run at a high frequency.